1. Field of the Invention
The present invention relates to a control apparatus for a power train which includes, integrated within a casing, a shift position detecting device for detecting a shift position that is changed in accordance with operation by the driver, an electronic control unit (hereinafter referred to as the “ECU”) for controlling the power train based on at least a detection signal representing a vehicle running state, and a connector for connecting to an electrical unit outside the casing. The term “power train” as used herein refers to an engine as a driving unit, an automatic transmission (hereinafter, also referred to as “A/T”) which automatically executes a starting operation or gear shifting operation, a semi-automatic transmission in which the starting operation is automated while the gear shifting operation is carried out manually, a continuously variable transmission which is capable of varying the speed stage over a continuum, the combination of an internal combustion engine and electric motor in a hybrid drive train, or a motor for driving an electric vehicle.
2. The Related Art
The vehicle-mounted A/T, which is one such power train, is controlled by operation of a shift unit including a hydraulic controller responsive to an operation by the driver, and by an ECU for controlling the A/T in accordance with a vehicle running condition detection signal. The ECU is mounted within a vehicle compartment or an engine compartment, and a neutral start switch (hereinafter referred to as the “N switch”) and a position sensor, which are electric devices used for control, are located outside the A/T case, while sensors for engine speed and oil temperature, solenoids and other devices are in general disposed within the A/T case. Accordingly, the respective electric devices and the ECU are electrically connected through a wire harness.
FIG. 15 is a diagram showing schematically and conceptually the electric connection between various electric devices and the ECU in a conventional A/T. As shown in FIG. 15, wiring of the various sensors in the A/T case (not shown) is gathered together by a wire harness a, which is wiring internal to the A/T case and extending therethrough to outside the A/T case. Furthermore, wirings b for solenoids provided in a valve body within the A/T case extend out of the A/T case individually, and wiring d of an N-switch integrated position sensor (shift position detecting sensor) c provided on an outer face of the A/T case is directly connected to an ECU f through a wire harness e.
In a wiring structure such as shown in FIG. 15, a number of wire harnesses and connectors are necessary for electric connection, so that they not only add to the weight, but also to the cost and, furthermore, require time for mounting design and vehicle installation.
For the foregoing reason, Japanese Patent Application Laid-Open No. HEI 5-196130 proposes simplification of the wiring structure by integrating the shift position detecting sensor with the ECU. According to this patent publication, complicated harness connections can be eliminated and production costs can be reduced, thereby improving mountability.
Incidentally, because the shift position detecting sensor and the ECU have different mounting positions and connector positions depending on the A/T, the layouts thereof are required to be easily and flexibly changeable to correspond to the A/T with which they are to be used.
However, in the integrated structure of the shift position detecting sensor and the ECU disclosed in the aforementioned patent publication, it is difficult to change the layout easily and flexibly to correspond to the A/T with which it is to be mounted. In particular, since, in the integrated structure in the aforementioned patent publication, a fixed contact of the shift position detecting sensor and a circuit board of the ECU are on a single common board, it is extremely difficult to change the layout flexibly to correspond to the A/T with which it is to be mounted.
Because the ECU with the shift position detecting device, in which such a shift position detecting sensor is integrated, is installed and fixed on an outer face of the A/T case, since the A/T is disposed within the engine compartment, the ECU with the shift position detecting device is also disposed within the engine compartment. The engine compartment accommodates not only an engine but also various other devices, so that installation space for the ECU with the shift position detecting device is limited to an extremely narrow space. Therefore, the ECU with the shift position detecting device is required to be formed as compactly as possible so as not to interfere with other the devices in the engine compartment. However, with the integrated structure of the shift position detecting sensor and the ECU disclosed in the aforementioned patent publication, no special consideration has been paid to compactness, and it cannot be said that measures were taken to form the ECU with the shift position detecting device as compactly as possible.
Further, because the shift position detecting sensor and the ECU each have various different shapes, if the shift position detecting sensor is integrated with the ECU, the integrated structure of the shift position detection sensor and the ECU is required to be easily and flexibly changeable to achieve as much compactness as possible.
However, with the integrated structure of the shift position detecting sensor and the ECU disclosed in the aforementioned patent publication, it is difficult to change the integrated structure to correspond to the respective shapes of the shift position detecting sensor and the ECU. In particular, since, in the integrated structure in the aforementioned patent publication, the fixed contact of the shift position detecting sensor and the circuit board of the ECU are mounted on a single common board, it is extremely difficult to change the integrated structure to correspond to the respective shapes of the shift position detecting sensor and the ECU.
Additionally, if an apparatus in which the shift position detecting sensor is integrated with the ECU is installed, for example, on an outer face of the A/T case within the engine compartment or within a valve body of the A/T, it is necessary to protect the ECU from severe heat within the engine compartment and from heat generated from a plurality of devices mounted on the control board of the ECU, to ensure accurate operation of the ECU. Thus, the control board of the ECU must be formed of a material having a high heat dissipation capacity and heat resistance.
In the integrated structure disclosed in the aforementioned patent publication, it is unavoidable that material having a high heat dissipation capacity and heat resistance must be used. In other words, since processing is not easy, it becomes necessary that a single common board be used that forms the fixed contact of the shift position detecting sensor and the ECU. If such a difficult to process material is employed as the board of the aforementioned integrated structure, it is extremely difficult to change it easily and flexibly, to correspond to the respective shapes of the shift position detecting sensor and the ECU. Therefore, a problem of dead space in the casing which accommodates the shift position detecting sensor and the ECU is created.
Furthermore, if it is extremely difficult to make the shape of such a single common board correspond to the respective shapes of the shift position detecting sensor and the ECU, it is difficult to electrically connect the shift position detecting device to the control unit flexibly and securely in accordance with the shape of the shift position detecting device or the shape of the control unit.
Further, the engine compartment accommodates not only an engine but also various other kinds of devices, and therefore the ECU installation space in which the ECU with the shift position detecting device is fixed is limited to a very small space. Therefore, the above-described ECU with the integrated shift position detecting device and shift position detecting sensor is required to be as compact as possible so as not to interfere with the other devices in the engine compartment. However, no special attention has been paid to such a requirement for compactness, and therefore it cannot be said that the ECU and shift position detecting device have been made sufficiently compact.